Aqueous herbicidal concentrates

ABSTRACT

Herbicidal concentrate compositions containing a combination of herbicides are provided. In particular, the present invention relates to aqueous herbicidal concentrate compositions containing a particulate encapsulated acetanilide herbicide and a protoporphyrinogen oxidase inhibitor (PPO inhibitor).

REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional application Ser. No.61/932,199, filed Jan. 27, 2014, the entire disclosure of which isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to herbicidal concentratecompositions containing a combination of herbicides. In particular, thepresent invention relates to aqueous herbicidal concentrate compositionscontaining a particulate encapsulated acetanilide herbicide and aprotoporphyrinogen oxidase inhibitor (PPO inhibitor).

BACKGROUND OF THE INVENTION

The emergence of certain herbicide resistant weeds has generatedinterest in developing strategies to supplement the action of primaryherbicides such as glyphosate. Acetanilides herbicides are known aseffective residual control herbicides that reduce early season weedcompetition. In particular, acetanilide herbicides such as acetochlorprovide outstanding residual control of many grasses and broadleaf weedsincluding pigweed, waterhemp, lambsquarters, nightshade, foxtails, amongothers. Acetanilides are generally classified as seedling growthinhibitors. Seedling growth inhibitors are absorbed and translocated inplants from germination to emergence primarily by subsurface emergingshoots and/or seedling roots. Acetanilide herbicides typically do notoffer significant post-emergence activity, but as a residual herbicideprovide control of newly emerging monocots and small-seeded dicot weedspecies. This supplements the activity of post-emergent herbicides thatlack significant residual activity.

Crop injury caused by application of acetanilide herbicides necessitatedstrategies to reduce this effect. One strategy involved applying theacetanilide herbicide formulations after the emergence of the crop(i.e., post-emergent to the crop), but before the emergence of latergerminating weeds (i.e., pre-emergent to the weeds). However,application during this time window may cause foliar injury to the crop.Other strategies to reduce crop injury involved microencapsulating theacetanilide herbicide. Methods for producing microencapsulatedacetanilides are described in various patents and publications includingU.S. Pat. No. 5,925,595; U.S. Publication No. 2004/0137031; and U.S.Publication No. 2010/0248963.

Another class of herbicides that have effective residual control andactivity against persistent herbicide resistant weeds such as palmeramaranth (Amaranthus palmeri) include protoporphyrinogen oxidase (PPO)inhibitors. PPO inhibitors include herbicides such as acifluorfen,azafenidin, bifenox, butafenacil, carfentrazone-ethyl, flufenpyr-ethyl,flumiclorac, flumiclorac-pentyl, flumioxazin, fluoroglycofen,fluthiacet-methyl, fomesafen, lactofen, oxadiargyl, oxadiazon,oxyfluorfen, pyraflufen-ethyl, saflufenacil and sulfentrazone, salts andesters thereof, and mixtures thereof.

Herbicide compositions containing a combination of herbicides withmultiple modes of action and that can supplement the action of primaryherbicides such as glyphosate are especially suited for controllinggrowth of unwanted plants, including those with selected herbicideresistance.

Dilute tank mix compositions of encapsulated acetanilide herbicides andPPO inhibitors are known in the art. However, the mixes are typicallyprepared at the point of use by the end user. There remains a need forhighly concentrated herbicidal compositions containing encapsulatedacetanilide herbicides and PPO inhibitors that are convenient foragricultural workers to formulate as spray solutions and that avoid therisk of tank mixing errors.

Further, the stability of herbicidal concentrates of encapsulatedacetanilides are sensitive to the inclusion of further additivesincluding co-herbicides. Accordingly, there remains a need for highlyconcentrated herbicidal compositions containing encapsulated acetanilideherbicides and PPO inhibitors that can be economically produced whilehaving sufficient stability and that can be diluted to provide effectivespray formulation solutions for application to unwanted plants.

SUMMARY OF THE INVENTION

In one aspect, the present invention is directed to an aqueousherbicidal concentrate composition comprising:

microcapsules comprising an acetanilide herbicide, wherein theacetanilide herbicide concentration in the composition on an activeingredient basis is at least about 25 wt. %;

a water-soluble protoporphyrinogen oxidase inhibitor (PPO inhibitor);and

at least about 750 ppm of a pseudoplastic thickener based on the totalweight of the composition.

In another aspect, the present invention is directed to an aqueousherbicidal concentrate composition comprising:

microcapsules comprising an acetanilide herbicide, wherein theacetanilide herbicide concentration in the composition on an activeingredient basis is at least about 25 wt. %;

a water-soluble protoporphyrinogen oxidase inhibitor (PPO inhibitor);

a structure-breaking agent in a concentration of not more than about 3.5wt. %; and

a density adjusting agent, wherein the total concentration ofstructure-breaking agent and density adjusting agent is from about 7 wt.% to about 10 wt. %, from about 7.5 wt. % to about 9 wt. %, or fromabout 8 wt. % to about 9 wt. %.

In a further aspect, the present invention is directed to an aqueousherbicidal concentrate composition comprising:

microcapsules comprising an acetanilide herbicide, wherein theacetanilide herbicide concentration in the composition on an activeingredient basis is at least about 25 wt. %;

a water-soluble protoporphyrinogen oxidase inhibitor (PPO inhibitor);

at least about 750 ppm of a pseudoplastic thickener based on the totalweight of the composition;

a structure-breaking agent in a concentration of not more than about 3.5wt. %; and

a density adjusting agent, wherein the total concentration ofstructure-breaking agent and density adjusting agent is from about 7 wt.% to about 10 wt. %, from about 7.5 wt. % to about 9 wt. %, or fromabout 8 wt. % to about 9 wt. %.

In still another aspect, the present invention is directed to an aqueousherbicidal concentrate composition comprising:

microcapsules comprising a core material comprising an acetanilideherbicide and a shell wall material encapsulating the core material;

an aqueous phase comprising the acetanilide herbicide (unencapsulatedacetanilide) and a water-soluble protoporphyrinogen oxidase inhibitor(PPO inhibitor), wherein the total acetanilide herbicide concentrationin the composition on an active ingredient basis is at least about 25wt. %; the weight ratio of total acetanilide herbicide to PPO inhibitoris from about 1:10 to 10:1; and the concentration of the acetanilideherbicide in the aqueous phase is from about 0.5% to about 10% of thetotal weight of acetanilide herbicide.

Other objects and features will be in part apparent and in part pointedout hereinafter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Generally, the present invention is directed to aqueous herbicidalconcentrate compositions comprising a combination of at least oneencapsulated acetanilide herbicide and at least one PPO inhibitorherbicide.

One aspect of the present invention is to provide a highly concentratedherbicidal composition containing at least one encapsulated acetanilideherbicide and at least one PPO inhibitor that can be diluted to providean effective spray formulation solution. A highly concentratedcomposition reduces the volume of the liquid and associated packagingthat would otherwise be required for more dilute compositions. Thesmaller volume reduces space required to store and transport theconcentrate composition prior to sale or use. Further, a highlyconcentrated herbicidal composition containing both an acetanilideherbicide and PPO inhibitor is convenient for agricultural workers toformulate as spray solutions and avoids the risk of tank mixing errors.

Another aspect of the present invention is to provide a highlyconcentrated herbicidal composition containing both an encapsulatedacetanilide herbicide and PPO inhibitor that is stable and does notappreciably separate into phases, form precipitates, or gel uponstanding or storage. A stable and compatible highly concentratedherbicidal composition beneficially provides a uniform spray formulationsolution upon dilution without the need for excessive agitation.

In accordance with the present invention, the concentrate compositionscomprise a PPO inhibitor. PPO inhibitors include herbicides such asacifluorfen, azafenidin, bifenox, butafenacil, carfentrazone-ethyl,flufenpyr-ethyl, flumiclorac, flumiclorac-pentyl, flumioxazin,fluoroglycofen, fluthiacet-methyl, fomesafen, lactofen, oxadiargyl,oxadiazon, oxyfluorfen, pyraflufen-ethyl, saflufenacil andsulfentrazone, salts and esters thereof, and mixtures thereof. Some PPOinhibitor herbicides are available in their free forms, as salts, or asderivatized materials, for example, as esters. In various embodiments,the concentrate compositions comprise a water-soluble PPO inhibitor. Insome embodiments, the water-soluble PPO inhibitor is selected from thegroup consisting of water-soluble salts of fomesafen and acifluorfen. Incertain embodiments, the water-soluble PPO inhibitor is selected fromthe group consisting of sodium fomesafen and sodium acifluorfen. Instill further embodiments, the water-soluble PPO inhibitor comprisessodium fomesafen.

Typically, the aqueous herbicidal concentrate compositions of thepresent invention contain at least about 2 wt. %, at least about 4 wt.%, at least about 5 wt. %, at least about 6 wt. %, or at least about 8wt. % of the PPO inhibitor on an active ingredient basis. In these andother embodiments, the aqueous herbicidal concentrate compositionscontain from about 2 wt. % to about 20 wt. %, from about 4 wt. % toabout 20 wt. %, from about 5 wt. % to about 20 wt. %, from about 5 wt. %to about 15 wt. %, from about 5 wt. % to about 10 wt. %, from about 6wt. % to about 15 wt. %, or from about 6 wt. % to about 10 wt. % of thePPO inhibitor on an active ingredient basis.

The concentrate compositions also comprise an encapsulated acetanilideherbicide (e.g., microcapsules of acetanilide herbicides). Acetanilideherbicides include herbicides such as acetochlor, alachlor, butachlor,butenachlor, delachlor, diethatyl, dimethachlor, mefenacet, metazochlor,metolachlor, S-metolachlor, pretilachlor, propachlor, propisochlor,prynachlor, terbuchlor, thenylchlor and xylachlor, mixtures thereof andstereoisomers thereof. Some acetanilide herbicides are available intheir free forms, as salts, or as derivatized materials, for example, asesters. In various embodiments, the acetanilide herbicide is selectedfrom the group consisting of acetochlor, alachlor, butachlor,metolachlor, and S-metolachlor. In certain embodiments, the acetanilideherbicide is selected from the group consisting of acetochlor,metolachlor and S-metolachlor. In various embodiments, the acetanilideherbicide comprises acetochlor.

The aqueous herbicidal concentrate compositions of the present inventioncontain at least about 15 wt. %, at least about 20 wt. %, at least about25 wt. %, at least about 30 wt. %, or at least about 35 wt. % of theacetanilide herbicide on an active ingredient basis. In these and otherembodiments, the aqueous herbicidal concentrate compositions containfrom about 15 wt. % to about 40 wt. %, from about 20 wt. % to about 40wt. %, from about 20 wt. % to about 35 wt. %, from about 20 wt. % toabout 30 wt. %, from about 25 wt. % to about 40 wt. %, from about 25 wt.% to about 35 wt. %, from about 30 wt. % to about 40 wt. %, or fromabout 30 wt. % to about 35 wt. % of the acetanilide herbicide on anactive ingredient basis.

The weight ratio of total acetanilide herbicide to PPO inhibitor on anacid equivalence (a.e.) basis can be from about 1:10 to about 10:1, fromabout 1:8 to about 8:1, from about 1:6 to about 6:1. In variousembodiments, the weight of the acetanilide herbicide is greater than theweight of the PPO inhibitor. Thus, the weight ratio of total acetanilideherbicide to PPO inhibitor on an acid equivalence basis can be fromabout 2:1 to about 10:1, from about 2:1 to about 8:1, from about 3:1 toabout 10:1, from about 3:1 to about 8:1, from about 4:1 to about 10:1,from about 4:1 to about 8:1, from about 5:1 to about 10:1, or from about5:1 to about 8:1.

In general, at least a portion of the acetanilide herbicide component ofthe concentrate compositions of the present invention is encapsulated(e.g., in microcapsules). The encapsulated acetanilide herbicides foruse in the present invention may be prepared by contacting an aqueouscontinuous phase containing a polyamine component comprising a polyaminesource and a discontinuous oil phase containing the acetanilideherbicide and a polyisocyanate component comprising a polyisocyanatesource. A polyurea shell wall is formed in a polymerization reactionbetween the polyamine source and the isocyanate source at the oil/waterinterface thereby forming a capsule or microcapsule containing theacetanilide herbicide. Accordingly, the microcapsules comprising theacetanilide herbicide can comprise a polyurea shell wall.

The polyurea polymer shell wall of the microcapsules may be formed usingone or more polyisocyanates, i.e., having two or more isocyanate groupsper molecule. In some embodiments, the polyurea shell wall is formedusing a blend of at least two polyisocyanates. For example, the polyureashell wall is formed in an interfacial polymerization reaction using atleast one diisocyanate and at least one triisocyanate. A variety ofpolyisocyanates can be employed. For example, the polyisocyanatecomponent can comprise an aliphatic polyisocyanate such those based onhexamethylene diisocyanate (e.g., DESMODUR N 3200 and DESMODUR N 3215).

The polyamine source can be a single polyamine species or a mixture oftwo or more different polyamine species. In some embodiments of thepresent invention, the polyamine source consists essentially of aprincipal polyamine. As used herein, a principal polyamine refers to apolyamine consisting essentially of a single polyamine species. Thepolyisocyanate source can also be a single polyisocyanate species or amixture of two or more different polyisocyanate species. See, forexample, U.S. Pat. No. 5,925,595; U.S. Publication No. 2004/0137031; andU.S. Publication No. 2010/0248963, which are incorporated herein byreference.

In general, an aqueous dispersion of the acetanilide capsules ormicrocapsules may be produced by an interfacial polymerization reaction,either continuously or batchwise, using means known in the art. However,preferably a polyamine is polymerized with one or more polyisocyanatesat the interface of an oil-in-water emulsion. The discontinuous oilphase (also referred to herein as “internal phase”) preferably comprisesone or more polyisocyanates and a continuous aqueous phase (alsoreferred to herein as “external phase”) comprises the principal amine.The oil phase further comprises a core material that comprises theacetanilide herbicide as the active ingredient.

The oil-in-water emulsion is preferably formed by adding the oil phaseto the continuous aqueous phase to which an emulsifying agent ordispersant has been added (e.g., previously dissolved therein). Theemulsifying agent is selected to achieve the desired oil droplet size inthe emulsion. The size of the oil droplets in the emulsion is impactedby a number of factors in addition to the emulsifying agent employed anddetermines the size of microcapsules formed by the process. Theemulsifying agent is preferably a protective colloid. Polymericdispersants are preferred as protective colloids. Polymeric dispersantsprovide steric stabilization to an emulsion by adsorbing to the surfaceof an oil drop and forming a high viscosity layer which prevents dropsfrom coalescing. Polymeric dispersants may be surfactants and arepreferred to surfactants which are not polymeric, because polymericcompounds form a stronger interfacial film around the oil drops. If theprotective colloid is ionic, the layer formed around each oil drop willalso serve to electrostatically prevent drops from coalescing. SOKALAN(available from BASF), a maleic acid-olefin copolymer, is a preferredprotective colloid, as is INVALON (available from Huntsman) and AGNIQUENSC 11NP (available from BASF), which are naphthalene sulfonatecondensates.

Other protective colloids useful in this invention are gelatin, casein,polyvinyl alcohol, alkylated polyvinyl pyrrolidone polymers, maleicanhydride-methyl vinyl ether copolymers, styrene-maleic anhydridecopolymers, maleic acid-butadiene and diisobutylene copolymers, sodiumand calcium lignosulfonates, sulfonated naphthalene-formaldehydecondensates, modified starches, and modified cellulosics likehydroxyethyl or hydroxypropyl cellulose, and carboxymethyl cellulose.

It is advantageous to select a polyamine component and a polyisocyanatecomponent such that the polyamine has an amine functionality of at least2, i.e., 3, 4, 5 or more, and at least one of the polyisocyanates has anisocyanate functionality of at least 2, i.e., 2.5, 3, 4, 5, or moresince high amine and isocyanate functionality increases the percentageof cross-linking occurring between individual polyurea polymers thatcomprise the shell wall. In some embodiments, the polyamine has an aminefunctionality of greater than 2 and the polyisocyanate is a mixture ofpolyisocyanates wherein each polyisocyanate has an isocyanatefunctionality of greater than 2. In other embodiments, the polyaminecomprises a trifunctional polyamine and the polyisocyanate componentcomprises one or more trifunctional polyisocyanates. In yet otherembodiments, the shell wall is formed by the reaction between apolyisocyanate or mixture of polyisocyanates with a minimum average of2.5 reactive groups per molecule and a polyamine with an average of atleast three reactive groups per molecule. It is, moreover, advantageousto select concentrations of the polyamine component and thepolyisocyanate component such that the polyisocyanate component issubstantially completely reacted to form the polyurea polymer. Completereaction of the polyisocyanate component increases the percentage ofcross-linking between polyurea polymers formed in the reaction therebyproviding structural stability to the shell wall. These factors, i.e.,the ratio of weight of core material components compared to weight ofshell wall components, the mean particle sizes of the herbicidalmicrocapsules, the degree of crosslinking, among other factors, may beselected to affect the release rate profile of the population ofherbicidal microcapsules, thereby enabling the preparation of herbicidalmicrocapsules that balance enhanced crop safety and are stillefficacious for weed control.

The microencapsulated acetanilide can be prepared by the methodsdescribed in U.S. Publication No. 2010/0248963. In particular, themethod includes encapsulating core material comprising the acetanilideherbicide in a shell wall formed by reacting a polyamine component and apolyisocyanate component in a reaction medium in concentrations suchthat the reaction medium comprises a molar equivalent excess of aminegroups compared to the isocyanate groups. That is, the molar equivalentsratio of amine equivalents to isocyanate equivalents used in preparationof the shell wall of the microcapsules is greater than 1:1. For example,a molar equivalents ratio at least 1.01:1, or at least about 1.05:1 isused to ensure that the isocyanate is completely reacted. The ratio ofamine molar equivalents contained in the polyamine component toisocyanate molar equivalents contained in the polyisocyanate componentcan be from 1.01:1 to about 1.7:1, from 1.01:1 to about 1.6:1, from1.01:1 to about 1.5:1, from 1.01:1 to about 1.4:1, from 1.01:1 to about1.3:1, from 1.05:1 to about 1.7:1, from 1.05:1 to about 1.6:1, from1.05:1 to about 1.5:1, from 1.05:1 to about 1.4:1, or from 1.05:1 toabout 1.3:1.

The molar equivalents ratio of amine molar equivalents to isocyanatemolar equivalents is calculated according to the following equation:

$\begin{matrix}{{{Molar}\mspace{14mu} {Equivalents}\mspace{14mu} {Ratio}} = \frac{{amine}\mspace{14mu} {molar}\mspace{14mu} {equivalents}}{{isocyanate}\mspace{14mu} {molar}\mspace{14mu} {equivalents}}} & (1)\end{matrix}$

In the above equation (1), the amine molar equivalents is calculatedaccording to the following equation:

molar equivalents=Σ(polyamine weight/equivalent weight).

In the above equation (1), the isocyanate molar equivalents iscalculated according to the following equation:

isocyanate molar equivalents=Σ(polyisocyanate weight/equivalent weight).

The equivalent weight is generally calculated by dividing the molecularweight in grams/mole by the number of functional groups per molecules.For some molecules, such as triethylenetetramine (“TETA”) and4,4′-diisocyanato-dicyclohexyl methane (“DES W”), the equivalent weightis equal to the molecular weight divided by the number of functionalgroups per molecule. For example, TETA has a molecular weight of 146.23g/mole and 4 amine groups. Therefore, the equivalent weight is 36.6g/mol. This calculation is generally correct, but for some materials,the actual equivalent weight may vary from the calculated equivalentweight. In some components, for example, the biuret-containing adduct(i.e., trimer) of hexamethylene-1,6-diisocyanate, the equivalent weightof the commercially available material differs from the theoreticalequivalent weight due to, for example, incomplete reaction. Thetheoretical equivalent weight of the biuret-containing adduct (i.e.,trimer) of hexamethylene-1,6-diisocyanate is 159.5 g/mol. The actualequivalent weight of the trimer of hexamethylene-1,6-diisocyanate (“DESN3200”), the commercially available product, is about 183 g/mol. Thisactual equivalent weight is used in the calculations above. The actualequivalent weight may be obtained from the manufacturer or by titrationwith a suitable reactant by methods known in the art. The symbol, Σ, inthe amine molar equivalents calculation means that the amine molarequivalents comprises the sum of amine molar equivalents for allpolyamines in the reaction medium. Likewise, the symbol, Σ, in theisocyanate molar equivalents calculation means that the isocyanate molarequivalents comprises the sum of isocyanate molar equivalents for allpolyisocyanates in the reaction medium.

As reported in U.S. Publication No. 2010/0248963, it is believed,without being bound to any particular theory, that the combination ofincreased particle size and the shell characteristics resulting from alarge excess of unreacted amine groups significantly reduces the releaserate, which is in that case the amount of herbicide that the crop plantsare exposed to following application, thereby providing enhanced cropsafety and minimized crop plant injury. It is believed, without beingbound to any particular theory, that increased excess of amine groupsresults in a significant number of unreacted amine functional groupsthereby providing a shell having a large number of amine functionalgroups that are not cross-linked. It is believed that the resultingshell wall is flexible and resistant to rupturing such that the amountof herbicide that crop plants are initially exposed to upon applicationof a herbicidal formulation containing the microcapsules is reduced. Itis further believed that unreacted amine groups may reduce the number offissures or cracks in the shell wall thereby reducing leakage and flowof herbicide through the shell wall from the core.

Accordingly, in various embodiments, the molar concentration of aminegroups from the polyamine component and the molar concentration ofisocyanate groups from the at least one polyisocyanate (i.e., onepolyisocyanate, a blend of two polyisocyanates, a blend of threepolyisocyanates, etc.) in the reaction medium is such that the ratio ofthe concentration of amine molar equivalents to the concentration ofisocyanate molar equivalents is at least about 1.1:1. In variousembodiments, the molar equivalents ratio of amine molar equivalents toisocyanate molar equivalents can be at least about 1.15:1, or even atleast about 1.20:1. In some embodiments, the molar equivalents ratio isless than about 1.7:1, less than about 1.6:1, less than about 1.5:1,less than about 1.4:1, or even less than about 1.3:1. In variousembodiments, the molar equivalents ratio of amine molar equivalents toisocyanate molar equivalents in the polymerization medium is from 1.1:1to about 1.7:1, from 1.1:1 to about 1.6:1, from 1.1:1 to about 1.5:1,from 1.1:1 to about 1.4:1, from 1.1:1 to about 1.3:1, from about 1.15:1to about 1.7:1, from about 1.15:1 to about 1.6:1, from about 1.15:1 toabout 1.5:1, from about 1.15:1 to about 1.4:1, from about 1.15:1 toabout 1.3:1, from 1.2:1 to about 1.7:1, from 1.2:1 to about 1.6:1, from1.2:1 to about 1.5:1, from 1.2:1 to about 1.4:1, or from 1.2:1 to about1.3:1. Examples of typical ratios include 1.1:1, 1.15:1, 1.2:1, 1.25:1,1.3:1, 1.35:1, 1.4:1, 1.45:1 and 1.5:1.

Generally, the microcapsules can be characterized as having a meanparticle size of at least about 2, 3, 4, 5, 6, 7, 8, 9 or 10 μm. Forexample, the microcapsules have a mean particle size range of from about2 μm to about 15 μm, from about 2 μm to about 12 μm, or from about 6 μmto about 15 μm. The capsules or microcapsules are essentially sphericalsuch that the mean transverse dimension defined by any point on asurface of the microcapsule to a point on the opposite side of themicrocapsule is essentially the diameter of the microcapsule. The meanparticle size of the microcapsules can be determined by measuring theparticle size of a representative sample with a laser light scatteringparticle size analyzer known to those skilled in the art. One example ofa particle size analyzer is a Coulter LS Particle Size Analyzer.

Further in accordance with the methods described in U.S. Publication No.2010/0248963, encapsulated acetanilides may be prepared wherein theparticles (i.e., capsule or microcapsules) are characterized as having amean particle size of at least about 7 μm. Particles of themicroencapsulated acetanilide can be characterized as having a meanparticle size of at least about 8 μm, at least about 9 μm, or at leastabout 10 μm. In various embodiments, the particles of the encapsulatedacetanilide are characterized as having a mean particle size that isless than about 15 μm or less than 12 μm. In view thereof, themicroencapsulated acetanilide can be characterized as having a meanparticle size of from about 7 μm to about 15 μm, from about 7 μm toabout 12 μm, from about 8 μm to about 12 μm, or from about 9 μm to about12 μm. In particularly preferred embodiments, the range varies fromabout 9 μm to about 11 μm.

In certain embodiments, the core material may further comprise one ormore compounds for release (e.g., an acetanilide and one or moreadditives compatible therewith which act to enhance its bioefficacy onweeds and/or reduce crop injury). For example, in some embodiments, thecore material optionally comprises a safener. Suitable safeners include,for example, furilazole((RS)-3-(dichloroacetyl)-5-(2-furanyl)-2,2-dimethyl-1,3-oxazolidine95%), commercially available from Monsanto Company; AD 67(4-(dichloroacetyl)-1-oxa-4-azaspiro[4,5]decane); benoxacor (CGA 154281,(RS)-4-dichloroacetyl-3,4-dihydro-3-methyl-2H-1,4-benzoxazine);cloquintocet-mexyl (CGA 184927, (5-chloroquinolin-8-yloxy)acetic acid);cyometrinil (CGA 43089, (Z)-cyanomethoxyimino(phenyl)acetonitrile);cyprosulfamide (N[4-(cyclopropylcarbamoyl)phenylsulfonyl]-o-anisamide);dichlormid (DDCA, 825788, N,N-diallyl-2,2-dichloroacetanilide);dicyclonon((RS)-1-dichloroacetyl-3,3,8a-trimethylperhydropyrrolo[1,2-a]pyrimidin-6-one);dietholate (O,O-diethyl O-phenyl phosphorothioate) fenchlorazole-ethyl(HOE 70542,1-(2,4-dichlorophenyl)-5-trichloromethyl-1H-1,2,4-triazole-3-carboxylicacid); fenclorim (CGA 123407 4,6-dichloro-2-phenylpyrimidine); flurazole(benzyl 2-chloro-4-trifluoromethyl-1,3-thiazole-5-carboxylate);fluxofenim (CGA 133205, 4′-chloro-2,2,2-trifluoroacetophenone(EZ)-O-1,3-dioxolan-2-ylmethyloxime); isoxadifen(4,5-dihydro-5,5-diphenyl-1,2-oxazole-3-carboxylic acid); mefenpyr((RS)-1-(2,4-dichlorophenyl)-5-methyl-2-pyrazoline-3,5-dicarboxylicacid); mephenate (4-chlorophenyl methylcarbamate); MG 191; naphthalicanhydride; oxabetrinil (CGA 92194, and(Z)-1,3-dioxolan-2-ylmethoxyimino(phenyl)acetonitrile).

In general, the encapsulated acetanilide herbicide particles comprise awater-immiscible, agricultural chemical-containing core materialencapsulated by a polyurea shell wall, which is preferably substantiallynon-microporous, such that core material release occurs by a moleculardiffusion mechanism, as opposed to a flow mechanism through a pore orrift in the polyurea shell wall. As noted herein, the shell wall maypreferably comprise a polyurea product of a polymerization of one ormore polyisocyanates and a principal polyamine (and optional auxiliarypolyamine). Typically, the encapsulated acetanilide herbicide particles(e.g, capsules or microcapsules) are dispersed in a liquid medium,preferably water. The acetanilide herbicide loading of the encapsulatedacetanilide herbicide dispersion is typically from about 5% to about 50%by weight on an active ingredient basis, such as 5%, 10%, 15%, 20%, 25%,30%, 35%, 40%, 45% or even 50% by weight on an active ingredient basis.The aqueous herbicidal concentrate is prepared by combining the aqueousdispersion of encapsulated acetanilide herbicide particles and PPOinhibitor component.

The water-soluble PPO inhibitor component may be prepared by adding theacid herbicide (e.g., fomesafen) to water and then adding an appropriatebase (e.g., sodium hydroxide) with agitation to prepare a solution ofthe water-soluble PPO inhibitor salt. The resulting solution is thenmixed with the encapsulated acetanilide herbicide dispersion to form theaqueous herbicidal concentrate composition.

The encapsulated acetanilide herbicide dispersion and the aqueousherbicidal concentrate compositions of the present invention may containone or more additives. For example, in various embodiments, theacetanilide herbicide dispersion and/or the aqueous herbicidalconcentrate compositions comprise one or more of the followingadditives: dispersant(s), surfactant(s), thickener(s),structure-breaking agent(s), density adjusting agent(s), antifreezeagent(s), anti-packing agent(s), drift control agent(s),preservative(s), and antifoam agent(s).

In various aspects, the encapsulated acetanilide herbicide dispersionand, consequently, the aqueous herbicidal concentrate compositions ofthe present invention comprise one or more thickeners. In general,thickeners are useful in retarding the settling process by increasingthe viscosity of the aqueous phase. In various embodiments,pseudoplastic thickeners (i.e., shear-thinning thickeners) arepreferred, because they reduce dispersion viscosity during pumping,which facilitates the economical application and even coverage of thedispersion to an agricultural field using the equipment commonlyemployed for such purpose. A few examples of useful pseudoplasticthickeners include water-soluble, guar- or xanthan-based gums (e.g.Kelzan from CPKelco), cellulose ethers (e.g. ETHOCEL from Dow), andmodified cellulosics and polymers (e.g. Aqualon thickeners fromHercules). In some embodiments, the pseudoplastic thickener comprises awater-soluble gum selected from the group consisting of guar gum,xanthan gum, and a combination thereof. In certain embodiments, thepseudoplastic thickener comprises xanthan gum.

Some dispersions of encapsulated acetanilide herbicide known in the artcontain no more than about 500 ppm or about 600 ppm of thickener. Beyondthis concentration range the viscosity of the dispersion increases to apoint which may result in poor pumpability and possible gelling of theencapsulated acetanilide herbicide particles. However, contrary to thisunderstanding, it has been surprisingly discovered that when formulatingan aqueous herbicidal concentrate containing encapsulated acetanilideherbicide (e.g., microcapsules) and a PPO inhibitor (e.g., water-solublePPO), the thickener concentration exceeds this critical maximum by asignificant amount in order to provide a stable composition (i.e. acomposition of sufficiently high viscosity without significant phaseseparation). Accordingly, in various embodiments, the aqueous herbicidalconcentrate compositions comprise at least about 750 ppm, at least about800 ppm, at least about 850 ppm, at least about 900 ppm, or at leastabout 950 ppm of a thickener (e.g., pseudoplastic thickener) based onthe total weight of the composition. Usually, the concentration of thethickener is less than about 2000 ppm, less than about 1800 ppm, lessthan about 1500 ppm, less than about 1300 ppm, or less than about 1200ppm. In some embodiments, the concentration of the thickener is fromabout 800 ppm to about 1500 ppm or from about 900 ppm to about 1200 ppm.

In certain embodiments, the viscosity of the dispersion of encapsulatedacetanilide herbicide upon formulation may preferably range from about100 cps to about 600 cps, as tested with a Haake Rotovisco Viscometerand measured at about 10° C. by a spindle rotating at about 45 rpm. Morepreferably, the viscosity may range from about 100 cps to about 300 cps.

Dispersants are useful to inhibit the agglomeration and settling of themicrocapsules and are present during the interfacial polymerizationreaction used in preparation of the acetanilide microcapsules.Accordingly, in various embodiments, the encapsulated acetanilideherbicide dispersion and, consequently, the aqueous herbicidalconcentrate compositions of the present invention comprise one or moredispersants. Low molecular weight dispersants may solubilize acetanilidecapsule or microcapsule shell walls, particularly in the early stages oftheir formation, causing gelling problems. Thus, in some embodiments,the dispersants have relatively high molecular weights of at least about1.5 kg/mole, more preferably of at least about 3 kg/mole, and still morepreferably at least about 5, 10 or even 15 kg/mole. In some embodiments,the molecular weight may range from about 5 kg/mole to about 50 kg/mole.Dispersants may also be non-ionic or anionic. An example of a highmolecular weight, anionic polymeric dispersant is polymeric naphthalenesulfonate sodium salt, such as Invalon (formerly Irgasol, HuntsmanChemicals). Other useful dispersants as previously mentioned includegelatin, casein, ammonium caseinate, polyvinyl alcohol, alkylatedpolyvinyl pyrrolidone polymers, maleic anhydride-methyl vinyl ethercopolymers, styrene-maleic anhydride copolymers, maleic acid-butadieneand diisobutylene copolymers, sodium and calcium lignosulfonates,sulfonated naphthalene-formaldehyde condensates, modified starches, andmodified cellulosics like hydroxyethyl or hydroxypropyl cellulose, andsodium carboxy methyl cellulose.

It has been found that adjusting the dispersant concentration isimportant to achieving a stable concentrate. Surprisingly, it wasobserved that when a stable dispersion of encapsulated acetanilideherbicide is mixed with an aqueous concentrate of PPO inhibitor, theresulting mixture was unstable with phase separation occurring. Thus,simply mixing commercial encapsulated acetanilide concentrates and PPOinhibitor concentrates are not expected to provide stable concentratemixtures. Some stable formulations of encapsulated acetanilideherbicides are known to contain about 3 wt. % of total dispersant.Instead, in accordance with the invention, to provide stable aqueousherbicidal concentrate compositions, the total dispersant concentrationis increased to at least about 3.5 wt. % or at least about 3.75 wt. %(e.g., from about 3.5 wt. % to about 5 wt. % or from about 3.75 wt. % toabout 4.5 wt. %).

In order to enhance shelf stability and prevent gelling of the aqueousencapsulated acetanilide herbicide particles, particularly upon storagein high temperature environments, the liquid dispersions and,consequently, the aqueous herbicidal concentrate compositions preferablyinclude a structure-breaking agent. Gelling is a significant concern forsome encapsulated acetanilide herbicide dispersion because the processis difficult, if not impossible to reverse and can render the productunsuitable for dilution and application. Accordingly, in variousembodiments, the encapsulated acetanilide herbicide dispersion and,consequently, aqueous herbicidal concentrate compositions of the presentinvention comprise one or more structure-breaking agents. One preferredstructure-breaking agent is urea. To prevent gelling, in someembodiments, concentrate compositions include at least about 4, 5, or 6wt. %, and up to about 20 wt. % or up to about 10 wt. % (e.g., about 4wt. % to about 10 wt. %) of the structure-breaking agent. However, insome embodiments, it has been surprisingly discovered that whenformulating certain aqueous herbicidal concentrates of the presentinvention containing encapsulated acetanilide herbicide (e.g.,microcapsules) and a PPO inhibitor (e.g., water-soluble PPO), theconcentration of structure-breaking agent is no more than about 3.5 wt.%. Typically, at least about 1 wt. %, at least about 2 wt. %, or atleast about 2.5 wt. % of the structure-breaking agent is needed in theseand other embodiments.

Adjusting the density of the aqueous phase to approach the mean weightper volume of the microcapsules also slows down the settling process. Inaddition to their primary purpose, many additives may increase thedensity of the aqueous phase. Further increase may be achieved by theaddition of density adjusting agents such as sodium chloride andglycols. A preferred density adjusting agent is glycerin. The aqueousherbicidal concentrate compositions can have a concentration of densityadjusting agent that is from at least about 4 wt. %, but no more thanabout 10 wt. %. In various embodiments, the concentration of densityadjusting agent is from about 5 wt. % to about 10 wt. %, from about 5wt. % to about 8 wt. %, from about 5 wt. % to about 6.5 wt. %, fromabout 5.5 wt. % to about 7 wt. %, or from about 5.5 wt. % to about 6.5wt. %.

In addition to its structure-breaking properties, urea also functions asa density adjusting agent. In embodiments where urea is included as astructure-breaking agent, the total concentration of urea and densityadjusting agent other than urea (e.g., glycerin) is from about 6 wt. %to about 10 wt. %, from about 6.5 wt. % to about 10 wt. %, from about 7wt. % to about 10 wt. %, from about 7.5 wt. % to about 9 wt. %, or fromabout 8 wt. % to about 9 wt. %. In these embodiments, it has been foundthat this combination of urea and density adjusting agent (e.g.,glycerin) provides a stable aqueous herbicidal concentrate compositionthat is resistant to gelling and settling upon storage even though theconcentrations of these components are generally less than what istypically required to prepare a stable dispersion of encapsulatedacetanilide herbicide.

In some instances, the weight to volume ratio of encapsulatedacetanilide herbicide particles of preferred dimensions is approximatedby the density of the core material, where the density of the corematerial is from about 1.05 to about 1.5 g/cm³. Accordingly, in variousembodiments, the density of the concentrate aqueous phase is formulatedto within about 0.2 g/cm³ of the mean weight to volume ratio of theencapsulated acetanilide herbicide particles.

Surfactants can optionally be included in the aqueous herbicidalconcentrate composition. Suitable surfactants are selected fromnon-ionics, cationics, anionics and mixtures thereof. Examples ofsurfactants suitable for the practice of the present invention include,but are not limited to: alkoxylated tertiary etheramines (such as TOMAHE-Series surfactants); alkoxylated quaternary etheramine (such as TOMAHQ-Series surfactant); alkoxylated etheramine oxides (such as TOMAHAO-Series surfactant); alkoxylated tertiary amine oxides (such as AROMOXseries surfactants); alkoxylated tertiary amine surfactants (such as theETHOMEEN T and C series surfactants); alkoxylated quaternary amines(such as the ETHOQUAD T and C series surfactants); alkyl sulfates, alkylether sulfates and alkyl aryl ether sulfates (such as the WITCOLATEseries surfactants); alkyl sulfonates, alkyl ether sulfonates and alkylaryl ether sulfonates (such as the WITCONATE series surfactants);alkoxylated phosphate esters and diesters (such as the PHOSPHOLAN seriessurfactants); alkyl polysaccharides (such as the AGRIMUL PG seriessurfactants); alkoxylated alcohols (such as the BRIJ or HETOXOL seriessurfactants); and mixtures thereof.

Anti-packing agents facilitate redispersion of encapsulated acetanilideherbicide particles (e.g., microcapsules) upon agitation of aformulation in which the particles have settled. A microcrystallinecellulose material such as LATTICE from FMC is effective as ananti-packing agent. Other suitable anti-packing agents are, for example,clay, silicon dioxide, insoluble starch particles, and insoluble metaloxides (e.g. aluminum oxide or iron oxide). Anti-packing agents thatchange the pH of the dispersion are preferably avoided in at least someembodiments.

The pH of the aqueous herbicidal concentrate composition can range fromabout 7 to about 9, in order to minimize eye irritation of those personswho may come into contact with the composition in the course of handlingor application to crops. However, if components of a formulateddispersion are sensitive to pH, buffers such as disodium phosphate maybe used to hold the pH in a range within which the components are mosteffective. Additionally, a pH buffer such as citric acid monohydrate maybe particularly useful in some systems during the preparation ofencapsulated acetanilide herbicide, to maximize the effectiveness of aprotective colloid such as SOKALAN CP9.

Other useful additives include, for example, biocides or preservatives(e.g., PROXEL, commercially available from Avecia), antifreeze agents,and antifoam agents (such as Antifoam SE23 from Wacker Silicones Corp.or AGNIQUE DFM-111S available from BASF).

The aqueous herbicidal concentrate compositions of the present inventioncan comprise a combination of additives. For example, in variousembodiments, the aqueous herbicidal concentrate compositions comprise acombination of additives including a pseudoplastic thickener (e.g,xanthan gum), urea, glycerin, and a combination of dispersants (e.g., anaphthalene sulfonate condensate, a maleic acid-olefin copolymer andammonium caseinate). In certain embodiments, the aqueous herbicidalconcentrate compositions comprise a combination of additives includingthose listed in the table below with approximate concentration ranges:

Ingredient Concentration Range pseudoplastic thickener 800-1500 ppm(e.g., xanthan gum) Urea 2-3.5 wt. % Glycerin 5.5-7 wt. % Naphthalenesulfonate 3.75-4.5 wt. % condensate (Total combined (e.g., INVALON DAM),concentration) Maleic acid-olefin copolymer (e.g., SOKALAN CP9),Ammonium caseinate

In preparation of an aqueous herbicidal concentrate compositioncomprising one or more of the additives mentioned herein, the entireportion of the additive (e.g., thickener, dispersant, structure-breakingagent, density adjusting agent, etc.) may be added to the liquiddispersion of encapsulated acetanilide herbicide prior to combining withPPO inhibitor component. Alternatively, a first portion of additive maybe added during preparation of a stable liquid dispersion ofencapsulated acetanilide herbicide and a second portion may be addedduring preparation of the aqueous herbicidal concentrate composition(i.e., mixing of the dispersion of encapsulated acetanilide herbicideand PPO inhibitor or solution thereof).

In accordance with the present invention, it has been observed that thereadily extractable acetanilide herbicide in the aqueous phase of theconcentrate compositions can be from about 0.5% to about 10%, from about0.5% to about 5%, from about 0.5% to about 2%, from about 0.75% to about10%, from about 0.75% to about 5%, from about 0.75% to about 2%, fromabout 1% to about 10%, from about 1% to about 5%, or from about 1% toabout 2% by weight of the total acetanilide herbicide. Typically, theconcentration of readily extractable acetanilide herbicide inmicroencapsulated concentrates is much less than 0.5 by weight of thetotal acetanilide herbicide. Without being bound by theory, it isbelieved that the PPO inhibitor present in the aqueous phase increasesthe solubility of acetanilide herbicide (See Example 7) and results in ahigher concentration of readily extractable acetanilide herbicide.Readily extractable acetanilide can be determined by extracting theconcentrate composition with weak solvent such as an aliphatichydrocarbon solvent and analyzing the extract. Importantly, it has beenfound that crop safety and weed control efficacy are not adverselyaffected by this unexpected result.

Accordingly, another aspect of the present invention is directed to anaqueous herbicidal concentrate composition comprising microcapsulescomprising a core material comprising an acetanilide herbicide and ashell wall material encapsulating the core material; an aqueous phasecomprising the acetanilide herbicide (unencapsulated acetanilide) and awater-soluble protoporphyrinogen oxidase inhibitor (PPO inhibitor),wherein the total acetanilide herbicide concentration is at least about25 wt. % and the concentration of the acetanilide herbicide in theaqueous phase is from about 0.5% to about 10%, from about 0.5% to about5%, from about 0.5% to about 2%, from about 0.75% to about 10%, fromabout 0.75% to about 5%, from about 0.75% to about 2%, from about 1% toabout 10%, from about 1% to about 5%, or from about 1% to about 2% byweight of the total acetanilide herbicide. As noted, the weight ratio oftotal acetanilide herbicide to PPO inhibitor on an acid equivalence(a.e.) basis can be from about 1:10 to about 10:1, from about 1:8 toabout 8:1, from about 1:6 to about 6:1. In various embodiments, theweight of the acetanilide herbicide is greater than the weight of thePPO inhibitor. Thus, the weight ratio of total acetanilide herbicide toPPO inhibitor on an acid equivalence basis can be from about 2:1 toabout 10:1, from about 2:1 to about 8:1, from about 3:1 to about 10:1,from about 3:1 to about 8:1, from about 4:1 to about 10:1, from about4:1 to about 8:1, from about 5:1 to about 10:1, or from about 5:1 toabout 8:1.

The aqueous herbicidal concentrates disclosed herein are useful ascontrolled-release herbicides. Therefore, the present invention is alsodirected to a method of applying an application mixture, which is adilution of the concentrate composition, for controlling plant growth.The acetanilide herbicide loading in the application mixture istypically no more than about 5% by weight or from about 0.1% to about 5%by weight on an active ingredient basis, such as 5%, 4%, 3%, 2%, 1%,0.5% or 0.1% by weight on an active ingredient basis.

The application mixture may be applied to a field according to practicesknown to those skilled in the art. In some embodiments, the applicationmixture is applied to the soil, before planting the crop plants or afterplanting, but pre-emergent to the crop plants. Because the releasecharacteristics of encapsulated acetanilide herbicide particles areadjustable, the timing of release initiation (or increase release) canbe controlled thereby giving both commercially acceptable weed controland a commercially acceptable rate of crop injury.

The effective amount of encapsulated acetanilide herbicide and PPOinhibitor to be applied to an agricultural field is dependent upon theidentity of the herbicides, the release rate of the capsules ormicrocapsules, the crop to be treated, and environmental conditions,especially soil type and moisture. Generally, application rates ofacetanilide herbicides, such as, for example, acetochlor, are on theorder of about 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 kilograms ofherbicide per hectare, or ranges thereof, such as from 0.5 to 10kilograms per hectare, from 0.5 to 10 kilograms per hectare, from 0.5 to5 kilograms per hectare, or from 1 to 5 kilograms per hectare. In someembodiments, an application rate for sorghum, rice and wheat of fromabout 0.85 to about 1 kilograms per hectare is preferred.

Generally, application rates of PPO inhibitors herbicides, such as, forexample, sodium fomesafen, are on the order of about 0.05, 0.1, 0.5, 1,1.5, 2, 2.5, 3, 4 or 5 kilograms of herbicide per hectare, or rangesthereof, such as from 0.1 to 5 kilograms per hectare, from 0.5 to 2.5kilograms per hectare, or from 0.5 to 2 kilograms per hectare.

Application mixtures of the aqueous herbicidal concentrates arepreferably applied to an agricultural field within a selected timeframeof crop plant development. In various embodiments of the presentinvention, the application mixture prepared from an aqueous herbicidalconcentrate is applied post-emergence to crop plants. For purposes ofthe present invention, post-emergence to crop plants includes initialemergence from the soil, i.e., “at cracking”. In some embodiments, theapplication mixture is applied to a field from 1-40 days prior toplanting of the crop plant and/or pre-emergence (i.e., from planting ofthe crop plant up to, but not including, emergence or cracking) in orderto provide control of newly emerging monocots and small seeded dicotspecies without significant crop damage. In various embodiments, theapplication mixture prepared from an aqueous herbicidal concentrate ofthe present invention is applied pre-emergence to weeds.

Application mixtures of the aqueous herbicidal concentrates of thepresent invention are useful for controlling a wide variety of weeds,i.e., plants that are considered to be a nuisance or a competitor ofcommercially important crop plants, such as corn, soybean, cotton, drybeans, snap beans, potatoes, etc. In some embodiments, the applicationmixtures are applied before the weeds emerge (i.e., pre-emergenceapplication). Examples of weeds that may be controlled according to themethod of the present invention include, but are not limited to, MeadowFoxtail (Alopecurus pratensis) and other weed species with theAlopecurus genus, Common Barnyard Grass (Echinochloa crus-galli) andother weed species within the Echinochloa genus, crabgrasses within thegenus Digitaria, White Clover (Trifolium repens), Lambsquarters(Chenopodium berlandieri), Redroot Pigweed (Amaranthus retroflexus) andother weed species within the Amaranthus genus, Common Purslane(Portulaca oleracea) and other weed species in the Portulaca genus,Chenopodium album and other Chenopodium spp., Setaria lutescens andother Setaria spp., Solanum nigrum and other Solanum spp., Loliummultiflorum and other Lolium spp., Brachiaria platyphylla and otherBrachiaria spp., Sorghum halepense and other Sorghum spp., ConyzaCanadensis and other Conyza spp., and Eleusine indica. In someembodiments, the weeds comprise one or more glyphosate-resistantspecies, 2,4-D-resistant species, dicamba-resistant species and/or ALSinhibitor herbicide-resistant species. In some embodiments, theglyphosate-resistant weed species is selected from the group consistingof Amaranthus palmeri, Amaranthus rudis, Ambrosia artemisiifolia,Ambrosia trifida, Conyza bonariensis, Conyza canadensis, Digitariainsularis, Echinochloa colona, Eleusine indica, Euphorbia heterophylla,Lolium multiflorum, Lolium rigidum, Plantago lancelata, Sorghumhalepense, and Urochloa panicoides.

Certain crop plants such as soybean and cotton are less susceptible tothe action of acetanilide herbicides and PPO inhibitors than are weeds.In accordance with the present invention and based on experimentalevidence to date, it is believed that the controlled acetanilide releaserate from the encapsulated acetanilide herbicides in combination withcrop plants having reduced acetanilide susceptibility enables commercialcontrol of weeds and commercially acceptable rates of crop damage whenencapsulated acetanilide herbicides are applied to a field eitherpre-planting or pre-emergent to the crop plant. This enables the use ofseedling growth inhibitor acetanilide herbicides, or optionally seedlinggrowth inhibitor acetanilide herbicides in combination with a PPOinhibitor, in crop plant pre-planting and pre-emergence applications.

In some embodiments of the present invention, crop plants include, forexample, corn, soybean, cotton, dry beans, snap beans, and potatoes.Crop plants include hybrids, inbreds, and transgenic or geneticallymodified plants having specific traits or combinations of traitsincluding, without limitation, herbicide tolerance (e.g., resistance toglyphosate, glufosinate, dicamba, sethoxydim, PPO inhibitor, etc.),Bacillus thuringiensis (Bt), high oil, high lysine, high starch,nutritional density, and drought resistance. In some embodiments, thecrop plants are tolerant to organophosphorus herbicides, acetolactatesynthase (ALS) or acetohydroxy acid synthase (AHAS) inhibitorherbicides, synthetic auxin herbicides and/or acetyl CoA carboxylase(ACCase) inhibitor herbicides, In other embodiments the crop plants aretolerant to glyphosate, dicamba, 2,4-D, MCPA, quizalofop, glufosinateand/or diclofop-methyl. In other embodiments, the crop plant isglyphosate and/or dicamba tolerant. In some embodiments of the presentinvention, crop plants are glyphosate and/or glufosinate tolerant. Insome other embodiments, the crop plants are glyphosate, glufosinate anddicamba tolerant. In these and other embodiments, the crop plants aretolerant to PPO inhibitors.

Particularly preferred crop species are cotton and soybean. Inembodiments where the crop is cotton, it is preferred to apply theapplication mixture at planting to before crop emergence, beforeplanting of the crop (e.g., 1-4 weeks before planting crop), and/orafter the crop has emerged (e.g., using a shielded sprayer to keepapplication mixture off of the crop). In embodiments where the crop issoybean, it is preferred to apply the application mixture at planting tobefore crop emergence, before planting of the crop (e.g., 1-4 weeksbefore planting crop), and/or after the crop has emerged.

EXAMPLES

The following non-limiting examples are provided to further illustratethe present invention.

Example 1

An aqueous herbicidal concentrate composition was prepared according tothe protocol described in this example.

A dispersion of microencapsulated acetochlor was prepared as follows.The internal phase was prepared with the components and amounts shown inTable 1-1. The percentages indicate the approximate weight percentage ofeach component in the final aqueous herbicide concentrate composition.

TABLE 1-1 Internal Phase Components wt. % in final wt. % active in finalwt. % concentrate concentrate Ingredient active composition compositionAcetochlor 95.80 31.57 30.24 ISOPAR M 100 1.63 1.63 (solvent, C₁₁- C₁₆isoalkanes) DESMODUR N 3215 100 2.3 2.3 (aliphatic isocyanate based onhexamethylene diisocyanate)

To prepare the internal phase of the acetochlor microcapsules,acetochlor was charged to a mixing vessel. Next, the solvent ISOPAR Mwas charged to the mixing vessel, followed by the DESMODUR N 3215polyisocyanate. The solution was agitated to obtain a clear homogenoussolution. The solution may be sealed within the mixing vessel and storeduntil needed. Prior to use, the mixture was heated to 50° C. in an oven.

The external aqueous phase was prepared containing the components andamounts shown in Table 1-2:

TABLE 1-2 External Phase Components wt. % in final wt. % active in finalconcentrate concentrate Ingredient wt. % active composition compositionGlycerin 100 2.42 2.42 SOKALAN CP9 25 3.11 0.78 (maleic acid-olefincopolymer) Ammonium 100 0.08 0.08 Caseinate Citric Acid 50 0.22 0.11Water 100 34.65 34.65 triethylenetetramine 98 0.6 0.58 (TETA)

To prepare the external phase, a mixing vessel was charged with waterand the remaining external phase component other than TETA. The solutionwas agitated to obtain a clear homogenous solution. The solution may besealed within the mixing vessel and stored until needed. Prior to use,the mixture was heated to 50° C. in an oven.

The interfacial polymerization medium was prepared by first charging theexternal phase (without TETA) to a Waring blender cup that has beenpreheated to 50° C. The commercial Waring blender (Waring ProductsDivision, Dynamics Corporation of America, New Hartford, Conn., Blender700) was powered through a 0 to 120 volt variable autotransformer. Theblender mix speed was varied by controlling power to the blender. Theinternal phase was added to the external phase over a 16 second intervaland blending was continued to obtain an emulsion.

To initiate polymerization and encapsulation of the internal phase, TETAwas added to the emulsion over a period of about 5 seconds. The blenderspeed is then reduced to a speed which just produces a vortex forapproximately five to fifteen minutes. The emulsion was then transferredto a hot plate and stirred. The reaction vessel is covered andmaintained at about 50° C. for approximately two hours which has beenfound is sufficient time for the isocyanate to react essentiallycompletely.

The capsule slurry is then allowed to cool to close to room temperature.The components shown in Table 1-3 with the exception of the buffer arepreviously premixed with a high speed mixer (Waring Blender or CowlesDissolver). The resulting stabilizer premix is then added to the capsuleslurry to stabilize the dispersion of microcapsules. Finally, the bufferis added and the mixture is stirred for at least 15 minutes untilvisually homogeneous.

TABLE 1-3 Stabilizer Components wt. % in wt. % active in concentrateconcentrate Ingredient wt. % active composition composition Glycerin 1004.04 4.04 KELZAN CC 100 0.096 0.096 (xanthan gum) Urea 50 4.5 2.25INVALON DAM 40 7.22 2.89 (naphthalene sulfonate condensate) AGNIQUEDFM-111S 100 0.001 0.001 (silicone based defoamer) PROXEL GXL 100 0.060.06 (solution of 1,2- benzisothiazolin-3-one Caustic 20 0.02 0.004Disodium phosphate 100 0.60 0.60

This dispersion of acetochlor microcapsules was prepared to have anexcess molar equivalents ratio of amine molar equivalents to isocyanatemolar equivalents and herbicide to shell wall component ratios. TETA hasan approximate equivalent weight of 36.6 g/mol. DESMODUR N 3215 has anapproximate equivalent weight of 181 g/mol. The mean particle size ofthe acetochlor microcapsules was approximately 10 microns.

The dispersion of acetochlor microcapsules was mixed with a solution ofsodium fomesafen. A stable concentrate without phase separation wasformed. The complete aqueous concentrate composition is provided below.

TABLE 1-4 Final Aqueous Herbicidal Concentrate Composition 1 wt. % inwt. % active in concentrate concentrate Ingredient wt. % activecomposition composition Acetochlor 95.80 31.57 30.24 Sodium Fomesafen97.70 6.88 6.72 ISOPAR M 100 1.63 1.63 (solvent, C₁₁- C₁₆ isoalkanes)DESMODUR N 3215 100 2.3 2.3 (aliphatic isocyanate based on hexamethylenediisocyanate) Glycerin 100 6.46 6.46 SOKALAN CP9 25 3.11 0.78 AmmoniumCaseinate 100 0.08 0.08 Citric Acid 50 0.22 0.11 Water 100 34.65 34.65triethylenetetramine 98 0.6 0.58 (TETA) KELZAN CC 100 0.096 0.096(xanthan gum) Urea 50 4.5 2.25 INVALON DAM 40 7.22 2.89 (naphthalenesulfonate condensate) AGNIQUE DFM-111S 100 0.001 0.001 (silicone baseddefoamer) PROXEL GXL 100 0.06 0.06 (solution of 1,2-benzisothiazolin-3-one Caustic 20 0.02 0.004 Disodium phosphate 100 0.600.60

Example 2

Additional aqueous herbicidal concentration compositions were preparedaccording to the protocol described in this Example 1. The compositionof each aqueous concentrate is provided in the tables below.

TABLE 2-1 Final Aqueous Herbicidal Concentrate Composition 2 ConcentrateNo. 2 wt. % in wt. % active in concentrate concentrate Ingredient wt. %active composition composition Acetochlor 95.8 31.57 30.24 Fomesafen 986.86 6.72 Isopar M 100 1.63 1.63 Desmodur N 3215 100 2.30 2.30 TETA 980.60 0.58 Glycerin 100 6.63 6.63 Sokalan CP9 (25%) 25 3.11 0.78 Ammonium100 0.06 0.06 Caseinate Citric Acid (50%) 50 0.22 0.11 Kelzan CC 1000.096 0.096 Urea 50 4.50 2.25 Invalon DAM 40 7.22 2.89 Agnique DFM-111S100 0.001 0.001 Proxel GXL 100 0.06 0.06 Caustic (20%) 20 3.06 0.61Disodium 100 0.60 0.60 Phosphate Water 100 34.51 Total 100

TABLE 2-2 Final Aqueous Herbicidal Concentrate Composition 3 ConcentrateNo. 3 wt. % in wt. % active in concentrate concentrate Ingredient wt. %active composition composition Acetochlor 95.8 31.57 30.24 Fomesafen 986.86 6.72 Isopar M 100 1.63 1.63 Desmodur N 3215 100 2.30 2.30 TETA 981.17 0.58 Glycerin 100 6.46 6.46 Sokalan CP9 (25%) 25 3.11 0.78 Ammonium100 0.06 0.06 Caseinate Citric Acid (50%) 50 0.22 0.11 Kelzan CC 1000.096 0.096 Urea 50 4.50 2.25 Invalon DAM 40 7.22 2.89 Agnique DFM-111S100 0.001 0.001 Proxel GXL 100 0.06 0.06 Caustic (20%) 20 3.06 0.61Disodium 100 0.60 0.60 Phosphate Water 100 34.11 Total 100.00

TABLE 2-3 Final Aqueous Herbicidal Concentrate Composition 4 ConcentrateNo. 4 wt. % in wt. % active in concentrate concentrate Ingredient wt. %active composition composition Acetochlor 95.8 31.57 30.24 Fomesafen 986.86 6.72 Isopar M 100 1.63 1.63 Desmodur N 3215 100 2.30 2.30 TETA 981.17 0.58 Glycerin 100 6.30 6.30 Sokalan CP9 (25%) 25 3.11 0.78 Ammonium100 0.06 0.06 Caseinate Citric Acid (50%) 50 0.22 0.11 Kelzan CC 1000.096 0.096 Urea 50 4.50 2.25 Invalon DAM 40 7.22 2.89 Agnique DFM-111S100 0.001 0.001 Proxel GXL 100 0.06 0.06 Caustic (20%) 20 3.06 0.61Disodium 100 0.60 0.60 Phosphate Water 100 34.27 Total 100

TABLE 2-4 Final Aqueous Herbicidal Concentrate Composition 5 ConcentrateNo. 5 wt. % in wt. % active in concentrate concentrate Ingredient wt. %active composition composition Acetochlor 95.8 31.57 30.24 Fomesafen 986.86 6.72 Isopar M 100 1.63 1.63 Desmodur N 3215 100 2.30 2.30 TETA 980.60 0.58 Glycerin 100 6.46 6.46 Sokalan CP9 (25%) 25 3.11 0.78 Ammonium100 0.06 0.06 Caseinate Citric Acid (50%) 50 0.22 0.11 Kelzan CC 1000.119 0.119 Urea 50 4.50 2.25 Invalon DAM 40 7.22 2.89 Agnique DFM-111S100 0.001 0.001 Proxel GXL 100 0.06 0.06 Caustic (20%) 20 3.06 0.61Disodium 100 0.60 0.60 Phosphate Water 100 34.66 Total 100

TABLE 2-5 Final Aqueous Herbicidal Concentrate Composition 6 ConcentrateNo. 6 wt. % in wt. % active in concentrate concentrate Ingredient wt. %active composition composition Acetochlor 95.8 31.57 30.24 Fomesafen 986.86 6.72 Isopar M 100 1.63 1.63 Desmodur N 3215 100 2.30 2.30 TETA 980.60 0.58 Glycerin 100 2.38 2.38 Sokalan CP9 (25%) 25 3.11 0.78 Ammonium100 0.06 0.06 Caseinate Citric Acid (50%) 50 0.22 0.11 Kelzan CC 1000.096 0.096 Urea 50 8.58 4.29 Invalon DAM 40 7.22 2.89 Agnique DFM-111S100 0.001 0.001 Proxel GXL 100 0.06 0.06 Caustic (20%) 20 3.06 0.61Disodium 100 0.60 0.60 Phosphate Water 100 34.68 Total 100

TABLE 2-6 Final Aqueous Herbicidal Concentrate Composition 7 ConcentrateNo. 7 wt. % in wt. % active in concentrate concentrate Ingredient wt. %active composition composition Acetochlor 95.8 31.57 30.24 Fomesafen98.5 6.82 6.72 Isopar M 100 1.63 1.63 Desmodur N 3215 100 2.30 2.3 TETA98 1.17 1.15 Glycerin 100 6.46 6.46 Sokalan CP9 25 3.11 0.78 Ammonium100 0.08 0.08 Caseinate Citric Acid 50 0.22 0.11 Kelzan CC 100 0.10 0.10Urea 50 4.50 2.25 Invalon DAM 40 7.22 2.89 Agnique DFM-111S 100 0.0010.001 Proxel GXL 100 0.06 0.06 Caustic (20%) 20 3.06 0.61 Disodium 1000.60 0.60 Phosphate Water 100 31.09 Total 100

TABLE 2-7 Final Aqueous Herbicidal Concentrate Composition 8 ConcentrateNo. 8 wt. % in wt. % active in concentrate concentrate Ingredient wt. %active composition composition Acetochlor 95.8 31.57 30.24 Fomesafen98.5 5.46 5.38 Isopar M 100 1.63 1.63 Desmodur N 3215 100 2.30 2.30 TETA98 1.17 1.15 Glycerin 100 6.46 6.46 Sokalan CP9 (25%) 25 3.11 0.78Ammonium 100 0.08 0.08 Caseinate Citric Acid (50%) 50 0.22 0.11 KelzanCC 100 0.10 0.10 Urea 50 4.50 2.25 Invalon DAM 40 7.22 2.89 AgniqueDFM-111S 100 0.001 0.001 Proxel GXL 100 0.06 0.06 Caustic (20%) 20 0.020.004 Disodium 100 2.45 0.49 Phosphate Water 100 35.49 Total 100

Example 3

Various properties of the aqueous herbicidal concentration compositionprepared in Examples 1 and 2 were measured. The results of thesemeasurements are provided in the table below. Readily extractableacetochlor was determined by extracting the concentrate composition withweak solvent such as an aliphatic hydrocarbon solvent and analyzing theextract. Particle size was measured with a Coulter LS Particle SizeAnalyzer. Viscosity was measured with a Haake Rotovisco Viscometer atabout 10° C. with a spindle rotating at about 45 rpm.

TABLE 3-1 Properties of Herbicidal Concentrate Compositions ReadilyExtractable Acetochlor (wt. % of Particle Specific HAAKE Concentratetotal Size pH Gravity Viscosity No. acetochlor) (microns) (neat) (at 20°C.) (cP) 1 0.512 9.3/9.3 9.1 1.1241 250 2 0.749 9.7/9.8 8.74 1.1228 2503 0.644 10.1/10.1 8.93 1.1222 251 4 0.476 9.6/9.7 8.96 1.1217 233 50.462 9.9/9.9 9.1 1.123 268 6 0.385 9.3/9.2 9.1 1.1184 167 7 Notmeasured ~10 7.5 1.121 225 8 Not measured ~10 7.5 1.115 250

Example 4

The aqueous herbicidal concentration compositions prepared in Examples 1and 2 were subjected to a heat aging test to investigate the effects ofprolonged storage on the viscosity of the compositions. A sample of eachherbicidal concentrate composition was stored at 40° C. for a period of8 weeks. No gelling was observed in any of the concentrate compositions.

Example 5

WARRANT, a commercially available concentrate composition ofmicroencapsulated acetochlor available from Monsanto Co., St. Louis,Mo., was mixed with a commercial concentrate composition of sodiumfomesafen. The table below provides the composition of the mixture.Combining these two concentrate compositions yielded an unstable mixturewith phase separation.

TABLE 5-1 Mixture of WARRANT and Fomesafen Concentrates wt. % in wt. %active in concentrate concentrate Ingredient wt. % active compositioncomposition Acetochlor 95.80 31.57 30.24 Sodium Fomesafen 97.70 6.886.78 ISOPAR M 100 1.63 1.63 (solvent, C₁₁- C₁₆ isoalkanes) DESMODUR N3215 100 2.3 2.3 (aliphatic isocyanate based on hexamethylenediisocyanate) Glycerin 100 7.19 7.19 SOKALAN CP9 25 2.16 0.54 AmmoniumCaseinate 100 0.04 0.04 Citric Acid 50 0.16 0.08 Water 100 33.30 33.30triethylenetetramine 98 0.6 0.58 (TETA) KELZAN CC 100 0.05 0.05 (xanthangum) Urea 50 8.28 4.14 INVALON DAM 40 5.60 2.24 (naphthalene sulfonatecondensate) AGNIQUE DFM-111S 100 0.001 0.001 (silicone based defoamer)PROXEL GXL 100 0.05 0.05 (solution of 1,2- benzisothiazolin-3-oneCaustic 20 0.02 0.004 Disodium phosphate 100 0.17 0.17

Example 6

A series of field trials were conducted at a variety of locations. Thesoil texture at these sites ranged from silty loam, silty clay loam, tosandy silt loam and sandy loam. The objective of the experiment was toevaluate the weed efficacy and length of residual efficacy of the eachstandalone herbicide compared to the herbicide combinations. Theexperiments were conducted in a randomized complete block design. Fourreplications were completed per treatment. Time of application waspre-emergence to weeds, and treatments were applied using a back-pack ortractor mounted sprayer. Application mixtures prepared from concentratecomposition 7 described in Example 2 were applied under field conditionsat an application rate of 1.363 lb of active ingredient (a.i.) per acre.For comparison, field trials with application mixtures of fomesafen andWARRANT were also performed.

Percent weed control by weed species was observed at four weeks aftertreatment (WAT). Weed control was determined as a percentage as comparedto untreated plants following a standard procedure where visualassessment of plant mortality and growth reduction is made by onespecially trained to make such assessments. Across the field trials, theresults for 16 broadleaf and 7 narrowleaf weed species were recorded.These included ABUTH (velvetleaf) in 9 trials; AMATA/AMAPA (palmeramaranth/waterhemp), Glyphosate-resistant (GR) AMAPA/AMATA, IPOSS(morningglory sps.), and ECHCG (Echinochola sps.) in 5 trials; DIGSS(Digitaria sps.) in 4 trials; CASOB (sicklepod), CHEAL (commonlambsquarters), and AMBEL (common ragweed) in 3 trials; POROL (commonpurslane) MOLVE (carpetweed), SETFA (giant foxtail), and SORHA(johnsongrass) in 2 trials; ACCOS (hophornbeam copperleaf), EPHSS(Euphorbia sps.), HIBTR (venice mallow), SIDSP (prickly sida), BRASS(signalgrass sps.), SORSS (sorghum sps.), and PESGL (pearl millet) in 1trial. The results of the field trials are presented in Tables 6-1 and6-2. Mean percent control and standard error are calculated by the leastsquares method. A summary of the results for a second field trial withsimilar weed species at four weeks after treatment is presented in Table6-3.

TABLE 6-1 Control of Weed Species for Acetochlor, Fomesafen, andConcentrate No. 7 in Field Trial 1 WARRANT (acetochlor) FomesafenConcentrate No. 7 1.125 lb/acre 0.25 lb/acre 1.363 lb/acre Weed Weed %Control Standard % Control Standard % Control Standard type Species(mean) Error (mean) Error (mean) Error Broadleaf ABUTH 55.6 5.8 63.7 5.875.5 5.8 ACCOS 80.0 1.0 93.8 1.0 92.5 1.0 AMAPA 71.9 4.8 92.5 4.8 100.04.8 AMAPG 80.5 7.8 87.8 7.8 96.6 7.8 AMATA 78.3 8.2 85.8 8.2 91.7 8.2AMATG 47.5 7.1 57.5 7.1 68.8 7.1 AMBEL 67.5 11.6 75.8 11.6 79.2 11.6CASOB 44.2 15.3 46.2 15.3 49.3 15.3 CHEAL 54.6 11.8 78.3 11.8 70.8 11.8EPHSS 85.0 1.6 100.0 1.6 100.0 1.6 HIBTR 70.0 5.0 75.0 5.0 85.0 5.0IPOHE 52.5 10.8 52.5 10.8 72.5 10.8 IPOLA 35.0 4.0 27.5 4.0 35.0 4.0IPOSS 46.9 19.0 63.1 19.0 76.8 19.0 MOLVE 87.1 4.1 90.6 4.1 96.5 4.1POROL 66.3 11.6 66.3 11.6 62.5 11.6 SEBEX 27.5 8.3 33.8 8.3 55.0 8.3SIDSP 93.8 2.6 98.3 2.6 100.0 2.6 Narrowleaf BRASS 97.5 3.1 99.5 3.196.0 3.1 DIGSA 90.8 9.5 65.3 9.5 97.4 9.5 DIGSS 96.3 2.8 99.0 2.8 100.02.8 ECHCF 98.1 7.0 71.9 7.0 99.9 7.0 ECHCG 89.5 12.0 66.8 12.0 96.0 12.0PESGL 52.5 2.2 100.0 2.2 100.0 2.2 SETFA 72.5 15.6 58.8 15.6 72.5 15.6SORHA 65.5 10.6 86.8 10.7 90.6 10.6 SORSS 90.0 2.2 99.8 2.2 100.0 2.2

TABLE 6-2 Field Trial 1 Results Summary Field Trial 1 Application RateBroadleaf Narrowleaf Active (lb a.i./acre) Control Control Fomesafen0.25 70 79 (0.28 kg/hectare) WARRANT 1.125 61 85 (1.26 kg/hectare)Concentrate No. 7 1.363 77 94 (fomesafen + (1.53 kg/hectare) acetochlor)

TABLE 6-2 Field Trial 2 Results Summary Field Trial 2 Application RateBroadleaf Narrowleaf Active (lb a.i./acre) Control Control Fomesafen0.25 63.6 66.3 (0.28 kg/hectare) WARRANT 1.125 43.2 86.2 (1.26kg/hectare) Concentrate No. 7 1.363 77 88.8 (fomesafen + (1.53kg/hectare) acetochlor)

Example 7

In this Example, the effect of fomesafen on the solubility of acetochlorwas measured at various fomesafen concentrations. The results are shownin Table 7-1.

TABLE 7-1 Solubility of Acetochlor in Fomesafen Solutions FomesafenAcetochlor Solution Concentration Concentartion in Solution (wt. %) (wt.%) 0 0.04 10 0.45 20 1.36 30 1.91 40 1.94

When introducing elements of the present invention or the preferredembodiments(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained. Asvarious changes could be made in the above compositions and methodswithout departing from the scope of the invention, it is intended thatall matter contained in the above description shall be interpreted asillustrative and not in a limiting sense.

Having described the invention in detail, it will be apparent thatmodifications and variations are possible without departing from thescope of the invention defined in the appended claims.

1. An aqueous herbicidal concentrate composition comprising:microcapsules comprising an acetanilide herbicide, wherein theacetanilide herbicide concentration in the composition on an activeingredient basis is at least about 25 wt. %; a water-solubleprotoporphyrinogen oxidase inhibitor (PPO inhibitor); and at least about750 ppm of a pseudoplastic thickener based on the total weight of thecomposition.
 2. The aqueous herbicidal concentrate composition of claim1 wherein the concentration of the pseudoplastic thickener is less thanabout 2000 ppm.
 3. The aqueous herbicidal concentrate composition ofclaim 1 wherein the concentration of the pseudoplastic thickener is fromabout 900 ppm to about 2000 ppm or from about 1000 ppm to about 1500ppm.
 4. The aqueous herbicidal concentrate composition of claim 1wherein the pseudoplastic thickener comprises a water-soluble gumselected from the group consisting of guar gum, xanthan gum, and acombination thereof.
 5. The aqueous herbicidal concentrate compositionof claim 1 wherein the weight ratio of total acetanilide herbicide toPPO inhibitor is from about 1:10 to 10:1
 6. The aqueous herbicidalconcentrate composition of claim 1 wherein the concentration of theacetanilide herbicide in the aqueous phase is from about 0.5% to about10% of the total weight of acetanilide herbicide.
 7. An aqueousherbicidal concentrate composition comprising: microcapsules comprisingan acetanilide herbicide, wherein the acetanilide herbicideconcentration in the composition on an active ingredient basis is atleast 25 wt. %; a water-soluble protoporphyrinogen oxidase inhibitor(PPO inhibitor); a structure-breaking agent in a concentration of notmore than about 3.5 wt. %; and a density adjusting agent, wherein thetotal concentration of structure-breaking agent and density adjustingagent is from about 7 wt. % to about 10 wt. %.
 8. The aqueous herbicidalconcentrate composition of claim 7 wherein the total concentration ofstructure-breaking agent and density adjusting agent is from about 7.5wt. % to about 9 wt. %, or from about 8 wt. % to about 9 wt. %.
 9. Theaqueous herbicidal concentrate composition of claim 7 wherein thestructure-breaking agent comprises urea.
 10. The aqueous herbicidalconcentrate composition of claim 7 wherein the density adjusting agentcomprises glycerin.
 11. The aqueous herbicidal concentrate compositionof claim 7 wherein the concentration of the structure-breaking agent isat least 2 wt. % or 2.5 wt. %.
 12. The aqueous herbicidal concentratecomposition of claim 7 further comprising a pseudoplastic thickener.13-18. (canceled)
 19. An aqueous herbicidal concentrate compositioncomprising: microcapsules comprising a core material comprising anacetanilide herbicide and a shell wall material encapsulating the corematerial; and an aqueous phase comprising the acetanilide herbicide anda water-soluble protoporphyrinogen oxidase inhibitor (PPO inhibitor),wherein the total acetanilide herbicide concentration in the compositionon an active ingredient basis is at least about 25 wt. %; the weightratio of total acetanilide herbicide to PPO inhibitor is from about 1:10to 10:1; and the concentration of the acetanilide herbicide in theaqueous phase is from about 0.5% to about 10% of the total weight ofacetanilide herbicide.
 20. The aqueous herbicidal concentratecomposition of claim 19 further comprising a pseudoplastic thickener.21-24. (canceled)
 25. The aqueous herbicidal concentrate composition ofclaim 1 wherein the composition further comprises a structure-breakingagent. 26-29. (canceled)
 30. The aqueous herbicidal concentratecomposition of claim 25 wherein the structure-breaking agent comprisesurea.
 31. The aqueous herbicidal concentrate composition of claim 1further comprising a density adjusting agent.
 32. The aqueous herbicidalconcentrate composition of claim 31 wherein the density adjusting agentcomprises glycerin. 33-38. (canceled)
 39. The aqueous herbicidalconcentrate composition of claim 1 wherein the acetanilide is selectedfrom the group consisting of acetochlor, alachlor, butachlor,butenachlor, delachlor, diethatyl, dimethachlor, mefenacet, metazochlor,metolachlor, S-metolachlor, pretilachlor, propachlor, propisochlor,prynachlor, terbuchlor, thenylchlor and xylachlor, mixtures thereof andstereoisomers thereof.
 40. The aqueous herbicidal concentratecomposition of claim 1 wherein the acetanilide is selected from thegroup consisting of acetochlor, alachlor, butachlor, metolachlor, andS-metolachlor. 41-43. (canceled)
 44. The aqueous herbicidal concentratecomposition of claim 1 wherein the concentration of the PPO inhibitor onan active ingredient basis is from about 2 wt. % to about 20 wt. %, fromabout 4 wt. % to about 20 wt. %, from about 5 wt. % to about 20 wt. %,from about 5 wt. % to about 15 wt. %, from about 5 wt. % to about 10 wt.%, from about 6 wt. % to about 15 wt. %, or from about 6 wt. % to about10 wt. %.
 45. The aqueous herbicidal concentrate composition of claim 1wherein the PPO inhibitor is selected from the group consisting ofacifluorfen, azafenidin, bifenox, butafenacil, carfentrazone-ethyl,flufenpyr-ethyl, flumiclorac, flumiclorac-pentyl, flumioxazin,fluoroglycofen, fluthiacet-methyl, fomesafen, lactofen, oxadiargyl,oxadiazon, oxyfluorfen, pyraflufen-ethyl, saflufenacil andsulfentrazone, salts and esters thereof, and mixtures thereof.
 46. Theaqueous herbicidal concentrate composition of claim 1 wherein thewater-soluble PPO inhibitor is selected from the group consisting ofwater-soluble salts of fomesafen and acifluorfen.
 47. The aqueousherbicidal concentrate composition of claim 1 wherein the water-solublePPO inhibitor comprises sodium fomesafen and the acetanilide comprisesacetochlor.
 48. The aqueous herbicidal concentrate composition of claim1 wherein the microcapsules comprising the acetanilide herbicidecomprise a polyurea shell wall.
 49. The aqueous herbicidal concentratecomposition of claim 48 wherein the polyurea shell wall is formed in apolymerization medium by a polymerization reaction between apolyisocyanate component comprising a polyisocyanate or mixture ofpolyisocyanates and a polyamine component comprising a polyamine ormixture of polyamines to form the polyurea.
 50. The aqueous herbicidalconcentrate composition of claim 49 wherein the polyisocyanate componentcomprises an aliphatic polyisocyanate.
 51. The aqueous herbicidalconcentrate composition of claim 49 wherein the ratio of amine molarequivalents contained in the polyamine component to isocyanate molarequivalents contained in the polyisocyanate component is at least about1.1:1, at least about 1.15:1, or at least about 1.2:1. 52-56. (canceled)